added url to json

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.cal.api/src/main/java/de/srsoftware/cal/api/Appointment.java

@@ -52,9 +52,10 @@ public interface Appointment {
 
 	/**
 	 * get a json representation of this Appointment
+	 * @param urlTemplate the url to put into the ical, with "{}" being replaced by the appointment id
 	 * @return a JSON Object
 	 */
-	JSONObject json();
+	JSONObject json(String urlTemplate);
 
 	/**
 	 * set of Links that point to related information